1.2: All About the Elements

Learning Objectives

• Explain how elements are arranged on the periodic table.
• Identify groups and periods on the periodic table.
• Provide the name of an element given its abbreviation.
• Determine the identity and number of atoms in a compound.

Basic Arrangement of Periodic Table

The periodic table has columns (known as groups) and horizontal rows are called periods and organizes all 118 elements currently identified. Each element is assigned a symbol that is either one or two letters. The first letter of the element symbol will always be capitalized, if there is a second letter, it will always be lowercase. Previously, some of the newly discovered elements (located in period seven on other tables) used three-letter symbols. These three-letter symbols corresponded to a Latin numbering system until the elements were given official names.

Languages of Element Names

Interestingly, different languages are used on the periodic table. Depending on your background, you might be more familiar with some elemental symbols than others. For example, hydrogen is represented by the symbol H. This element's name is derived from the Greek hydro, and genes which means to generate water. Other elemental symbols like copper (which has a symbol of Cu) are not so predictable. This particular element's name originated from the Latin cuprum (from the island of Cyprus). A variety of languages are displayed on the periodic table. For example, German roots are present in the element tungsten. The symbol for this element is W which corresponds to the German word, wolfram. For this course, you do not need to have these memorized but should be able to use the Periodic Table to convert between the name of the element and the element symbol.

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Meanings of Element Names

Many elements are named in honor of people. Some familiar names you might see are curium (Marie and Pierre Curie), einsteinium (Albert Einstein), and mendelevium (Dimitri Mendeleev). IUPAC (International Union of Pure and Applied Chemistry) requires these types of names to be done posthumously. In other words, the scientist who discovered the element could not name it after her/himself or anyone who is still currently living. Over the years, there have been two exceptions. The elements of seaborgium (Sg) and oganesson (Og) were named while Glen Seaborg and Yuri Oganessian were still living. Seaborgium was named in honor of an American nuclear chemist who synthesized the element plutonium. He is also credited with assisting the discovery of other elements like americium (element 95), curium (element 96), and fermium (element 100). His accomplishments encouraged his fellow researcher, Albert Ghiorso, to name Seaborgium in honor of him. As for element 118 (oganessian), a joint research commission of Russian and American scientists named this element for Russian physicist Yuri Oganessian. As of 2017, Oganessian is still living and is responsible for the discovery of superheavy elements.

It is acceptable to name an element in honor of a geographical location. Some notable Earth locations would include Am (americium, American continent), Ge (germanium, Germany), Fr (francium, France), and Eu (europium, European continent). Some scientists have ventured past Earth to name their elements in honor of other places. Examples of these would include Pu (plutonium, Pluto), U (uranium, Uranus), and Np (neptunium, Neptune).

Interpreting Chemical Formulas

Chemical formulas are used as a shorthand to represent the components of a compound. Each capital letter of a chemical formula indicates a different element. Subscripts and parentheses are used to indicate the number of atoms of each element that is present. If there is no number listed, it is assumed that there is only a single atom of that element. To represent a compound with 1 atom of magnesium and 2 atoms of chlorine the formula would be MgCl₂; no subscript is needed after magnesium because only one atom is present, the subscript 2 after the symbol for chlorine indicates that two atoms of chlorine are present. For further information, see the example below.

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Using the chemical formula below, identify the number of atoms for each element present.

Solution

The chemical formula shown contains three capital letters, one for each element it contains: sodium (Na), phosphorous (P), and oxygen (O). The subscripts after an element symbol indicate the number of atoms for that element. In this example, it means there are 3 atoms of sodium (Na). Parentheses are used to indicate that a portion of the formula is repeated. The number of repeats is indicated by the subscript after the parentheses. In this example, the subscript 2 indicates there are two sets of PO₄, and therefore 2 atoms of phosphorous (1 x 2) and 8 atoms of oxygen (4 x 2).

• 3 atoms of sodium
• 2 atoms of phosphorous
• 8 atoms of oxygen

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Contributors and Attributions

• Elizabeth R. Gordon (Furman University)

• Hayden Cox (Furman University)
• Erin Avram (Cleveland State University)